Example of treatment of a mixture of pollutants in industry

This innovative "One-pot" process consists in capturing gaseous pollutants in a physicochemical treatment whose liquid effluents are subsequently digested by the aerobic bio-purification process in the treatment plant.

(A)    Simultaneous process of absorption (capture) and organic chemical modification of Volatile Organic Compounds (organic and inorganic).
This operation is carried out in a single operation on a collection installation by physico-chemical washing.

(B)    The final destruction of the capture products after the simultaneous process of absorption and chemical modification
This ultimate operation (B) is carried out in a biological treatment plant.
The organic compounds present and formed During the condensation reaction are digested by the process of natural aerobic bio-purification of the purification plant.

The originality of the process resides firstly in the choice of the reagent which combines with the pollutants to be treated and secondly in the final natural destruction in the wastewater treatment plant that does not generate any new gaseous pollution.

The example below describes the treatment of a mixture of pollutants in a single operation

A gas scrubbing column joins the vents of three "pilot" reactors in chemical industry:

• Reactor 1 - Synthesis of an Acid Chloride
• Reactor 2 - Synthesis of methyl ethyl sulfide
• Reactor 3 - Decarboxylation of an Acid

Operating mode:

In the suction tank is charged the additional water determined in the worksheet corresponding to 20 volumes of the pure reagent and then in order the calculated amounts of alkaline solution of potassium hydroxide, then the 40% solution of the reagent.
The reaction medium displays a pH value> 11.
The circulation pump is activated then the gas flow valve is gradually released and controlled at the desired flow rate.
The end of the reaction is determined and controlled by pH <9.
The operations took place over a period of 10 hours with a gas flow rate of 500 m3/h.
The end of the reaction is controlled by pH-metry (about 9-10), and the absence of H2S and mercaptans checked with lead acetate paper and pH paper.

The clear, colorless and odorless reaction medium is then discharged to the plant's self-neutralization pit before being discharged to the network to be subjected to the aerobic bio-purification process in the treatment plant.

Results on the unfiltered reaction medium before rejection to the biological station of the site

• pH = 10.3;
• temperature 35 ° C
• COD: 298 mg/L
• BOD5: 695 mg/L

In this test, it is clear that for the destruction of sulfur compounds, treatment with bleach would return 12 times more expensive than treatment with the PTC system.
ClO2 or H2O2 treatments are even more expensive.

• This example of chemistry treatment includes:
• Complete elimination of sulfur compounds.
• Decarbonation (complete elimination of CO2).
• Complete elimination of hydrochloric acid.
• Complete removal of traces of thionyl chloride.
• The total elimination of the solvents present in the state of traces.

Cost of treatment 627 € whose:

• Soda: 503 €
• Reactive: 228 €

A similar competitor treatment with bleach would have cost € 1,030
For CO2 alone 1,582 liters of soda were consumed 30% for € 395

The flow calculation sheet to determine the quantities of reagents:

See also the examples of the DAVID Process - Odors